1. Field of Invention
This invention pertains to a control knob, particularly for automotive applications, with an indicator portion which remains a first color, such as white, during the day, but which appears illuminated at night to a second color, such as blue, the second color being variable as to both hue and intensity. An LED (light emitting diode) is included within the control knob, secured either to the control knob or the control shaft, to provide illumination to the indicator portion during the night.
2. Description of the Prior Art
In the prior art, control knobs, particularly control knobs in automotive applications, have had position indicators for indicating the rotational position of the knob. While paints and inks have frequently been used to provide such an indicator, this solution has not been resistant to abrasion. U.S. Pat. No. 5,450,653 entitled "Composite Knob with an Insertable Position Indicator" issued on Sep. 19, 1995 to Howie, Jr. discloses a composite knob with an insertable position indicator which would be more resistant to abrasion than simple paints or inks. The position indicator has a color contrasting to that of the knob. However, this indicator does not provide a first color, such as white, during the daytime, and a second distinct color, such as blue, during the nighttime.
U.S. Pat. No. 5,050,269 entitled "Control Knob" issued on Sep. 24, 1991 to Engstrom et al. discloses a control knob, apparently for a portable telephone or "walky-talky" type device, with an outer portion of reduced hardness molded over an inner portion with a blade portion extending through the outer portion to provide an indicator. This does not appear to provide for different colors of the indicator during daytime and nighttime.
U.S. Pat. No. 5,518,561 entitled "True Color Day-Night Graphics and Method of Assembly issued on May 21, 1996 to Rosa discloses a display panel with a light-emitting electroluminescent portion, but does not relate to control knobs, particularly for automotive applications.
Additionally, in the prior art, it has been a concern for the control knob indicator portion to be adequately illuminated during the nighttime. This has been of a particular concern for incandescent illumination, which generates considerable heat.
Similarly, in the prior art, the control knob indicator portions have not included entirely satisfactory methods for controlling both the brightness and color of the indicator portion of a control knob.
Additionally, in the prior art, it has been a substantial concern that the knobs not wobble in use, as this may be disconcerting to the user.
Other references of interest include U.S. Pat. No. 5,469,758 issued on Nov. 28, 1995 to Howie, Jr.; U.S. Pat. No. 5,259,267 issued on Nov. 9, 1993 to Jurewicz; U.S. Pat. No. 5,303,612 issued on Apr. 19, 1994 to Odom et al. ; U.S. Pat. No. 2,753,911 issued on Jul. 10, 1956 to Haslett; and U.S. Pat. No. 273,685 issued on Mar. 6, 1883 to Huntley.
Additionally, the following applications were filed on behalf of the present assignee and the disclosures of which are hereby incorporated by reference--U.S. patent application Ser. No. 08/746,989 entitled "Control Knob" was filed on Nov. 19, 1996, U.S. patent application Ser. No. 08/812,576 entitled "Illuminated Knob Assembly" was filed on Mar. 7, 1997, and U.S. patent application Ser. No. 09/048,770 entitled "Illuminated Knob Assembly" was filed on Mar. 26, 1998.